What is Stroke Length?
Stroke length is how far your body travels forward on each arm stroke.
It is like measuring the distance you move forward on each step or stride.
We can easily feel Stride Length and see it on land as we walk or run. It makes sense to us as Land Mammals. It’s the same idea for us in water, but we can’t feel it and we can’t see it directly. (Can fish feel their stride?) So we first have to learn some new forms of measurement and train ourselves to feel it, so that we can control it.
To give some starting reference point, in the local pool we may see common swimmers traveling somewhere between 0.70 to 1.20 meters on each stroke (in crawl stroke, that is). Of course, there will also be quite a few traveling far less. If there happen to be some well-developed (and tall) swimmers in there we might see strokes that carry them a bit farther.
It has been proposed that humans may not be physically capable of generating a crawl stroke that causes us to travel farther than our own height (assuming we are not simply kicking our way across the pool). Who knows!
Why should we care about Stroke Length?
You know the saying, “Two steps forward, one step back.”
Or have you ever tried to walk up a scree slope?
Or ever had your car stuck in the snow or mud?
I suppose if a person’s only goal is to burn calories in the water, then Stroke Length doesn’t matter. In that case, one might as well do water aerobics in place of swimming. But if a person actually wants to swim there is some sense of satisfaction in covering distance, and covering it more easily. There are definitely more pleasant and less pleasant ways to cover distance while swimming.
So, let’s assume swimmers want to move forward and cover some distance, and do it with less struggle rather than more. If we can enjoy it too, all the better.
Stroke Length is a measurement of how much traction we are getting on each stroke. A stroke length that is ‘too short’ is the equivalent of the car’s wheels spinning in the mud – in terms of water it means we are pushing water around more than pushing our body forward. It shows us how much our arms are slipping backward through the water instead of our body slipping forward through the water.
The water is loose and unstable like scree. It is thick and heavy like mud. It is also slippery like ice. Drag has all those negative features packaged together, working against our forward movement. Drag, like a mud pit, sucks up our limited energy while we go nowhere fast. Good technique is what allows us to escape that mud-pit of drag.
Good technique is defined by what produces minimal drag. Speed is a product of good technique, not the definition of it. Drag grabs shape, and therefore we reduce drag by improving the shape of our body. Minimal drag allows us to produce a longer stroke with less effort. If we have poor technique (poor body position and transitions), we create more drag which means we cannot produce such a long stroke with out excessive effort. If they have a stroke that has the same effect as a person trying to run through mud no wonder so many people experience swimming as an exhausting endurance activity!
Convinced that Stroke Length is important to pay attention to?
If you want swimming to be easier I hope so.
How do we measure Stroke Length?
In your home pool you need to take some measurements…
Measure the length of your pool. This will be LP.
Measure (or estimate the best you can) the distance of your push-off from the wall and glide until you begin the first, underwater catch and pull. This will be DG. [A clue: the backstroke flags should be at the 5 meter/yard mark in every competitive pool.]
An average fitness swimmer Glide Distance may be around 4 meters. A developed competitive swimmer may be around 5 meters or more. It can vary by skill but those estimates can get you close.
Now, after you push off and take that first underwater stroke (count that as stroke #0) count how many strokes it takes you to reach the other wall, without any extra glide when you are about to reach it. This will be your Stroke Count, or SC (aka SPL).
SL = (LP – DG) / SC
Hilal’s pool is 25 meters long. LP = 25.
She glides 4 meter to begin her first stroke underwater. DG = 4.
She counted her strokes on several laps to see that she takes about 22 strokes on average. SC = 22.
Hilal’s stroke length is calculated to be: SL = (25 – 4) / 22 = 0.95 meters long
Stroke Count is the number of strokes we take to get to the other side of the pool. By far most swimmers have the problem of taking too many strokes (= stroke length is too short), which immediately reveals how much excessive drag they are creating, as if they are swimming in mud. Believe it or not, those who are taking so many strokes and traveling slow are most likely using up far more energy than those traveling faster with fewer strokes. The (smooth) faster swimmers are often not working as hard as the slow ones. Don’t we want to know their secret?
This is the problem we solve by looking at Stroke Length and learning how to improve it.
In some cases a swimmer may develop a really looonnnggg stroke length – there is great value in developing that capability and using it as a drill, but the optimal stroke length for racing or for enjoyable distance swimming will not be found at that extreme. The optimal zone for racing short distance or long, or just going on and on in the most enjoyable way is somewhere between too short and too long.
And where is that magical zone?
We can point you in the right direction in the next part, but from there on, it will take some actual experimentation in the pool for you to dial in your ideal Stroke Length.
What is a good Stroke Length and what is a bad one?
Most people we see in the pool have far too short of a Stroke Length. A few keep theirs too long. Either extreme means wasted energy.
So we want to find just the right Stroke Length for each, because it varies a bit from person to person. The suitable Stroke Length for each of us is determined by a few factors we will discuss below (and more can be added if more customization is needed):
1. Suitable SL is determined first by our height, or better yet, our wingspan.
The first objectively measurable feature of truly good freestyle technique is Stroke Length. By a great deal of data crunching and observation we estimate that a good freestyle stroke should be within 55% to 70% of a swimmer’s wingspan (or height, if you only know that measurement – it is approximately the same, give +/- 5%, and sufficient for most swimmers to calculate by). It TI we call this the Green Zone.
Here is a chart showing the approximate Green Zone Stroke Count (SPL) in a 25 meter pool and a 50 meter pool.
This zone is calculated by taking 55% to 70% of Wingspan (or Height) and running it through a little algorithm. 55% would be the top of that Green Zone (the maximum SPL) and 70% is the bottom of that Green Zone (the minimum SPL).
Hilal has a 1.54 meters wingspan (and conveniently, she happens to be precisely 1.54 meters tall). From the previous example we see that she has an average SL of 0.95 meters per stroke.
WC% = SL / Wingspan (or Height) = 0.95 / 1.54 = 61%
We say that Hilal is converting 61% of her Wingspan into Stroke Length. At WC% = 61% her stroke is right in the middle of her Green Zone.
Is that a good SL for her?
Most likely it is good for some of her swimming, but we need to look at the next factor to decide what part it fits…
2. Suitable Stroke Length needs to fit the event we are swimming, and the way we intend to use our limited energy.
In other words, if we are aiming for short distance (like under 200 m) highest intensity we may aim for the shorter side of that range – say 55% to 65%. If we are aiming for a pleasant long-distance swim that may last a few hours we may aim for 60% to 70%. This is a guideline, of course. Humans and circumstances vary quite a bit.
In long-distance open-water swimming, for example, I will change up my Stroke Length depending on the conditions and my energy level. If there are waves, depending on which direction and in what form, I will change my Stroke Length so that I can blend with those waves rather than fight them because nature will always win. It saves far more energy to do this, than stick to a rigid Stroke Length. Because I train in a full set of SL and Tempo combinations, I can adjust both to keep Pace where I want while blending with those waves. This is a serious advantage over swimmers who have not trained themselves to handle a wide range of combinations. If a swimmer cannot control and adjust Stroke Length on command, he cannot keep Pace in changing conditions and control his energy expenditure at the same time.
Keep this in mind – no humans start with a naturally appropriate Stroke Length. We have NO instinct for this activity, though some seem to have a head start (talent) at figuring it out upon getting into the water. An appropriate stroke is absolutely a learned skill for humans. So just because you have an excessively short or excessively long stroke that currently feels ‘normal’ and therefore ‘comfortable’ to you – the discomfort you feel, the increase in heart rate or respiration it triggers, or the flat inability to achieve a more appropriate SL on first attempt is no reliable indication that your current stroke length should be held onto, or this new one rejected. You need to give the programming process time and a genuine effort to integrate the changes. In time, by design, your whole system adapts and it starts to yield the promised efficiency in a way you feel and appreciate. Anyone trying a new neuro-motor set of instructions will struggle in some way and thereby feel confusion or exhaustion quickly. It takes time – just like learning to play the piano – and it takes trust in the process you are applying yourself to. I would bet that just about everyone who says ‘I tried it, but it didn’t work for me’ did not, in fact, follow the neuro-motor programming process faithfully. The physiology and physics is universal to all of us and the programming process is designed on how humans work, not our personal style.
And wait… there is another factor that may urge us to shorten or lengthen the Stroke Length and find that it feels better in terms of requiring less energy…
3. The ratio of our ‘wingspan/height’ further influences where we will find our SL Sweet Spot.
A swimmer’s Green Zone, according to the chart, is about 5 SPL wide. But ideally, we want to dial that in to about 3 SPL to really know where to train for our particular goals. We would call this our SPL Sweet Spot. To do that, we can look at the wingspan/height ratio to give more clues.
Hilal’s wingspan shows her Green Zone to be 19, 20, 21, 22, 23 SPL (in a 25 m pool).
Her wingspan/height ratio is a perfect 1.00 so that suggests we look for her Sweet Spot 3 SPL to be right in the middle: 20, 21, 22 SPL.
If a swimmer’s wingspan/height ratio is .99 or less, she may find her sweet spot in the 55% to 60% range, or the upper half of the chart. If her wingspan/height ratio is above 1.03 she may find her sweet spot in the 60% to 70% range, or on the lower half of the chart. That yellow line in the chart above represents the W/H Ratio = 1.00.
Sung Yang has a wingspan of 2.11 meters and a height of 1.98 meters. This gives him a W/H Ratio of 1.06. He displayed an exceptional long stroke in his world record 1500 meter swims. He used an average SL of approximately 75% of his wingspan on the first 1400 meters and then shortened a bit to 67% for his final 100. (The numbers I just used are based on a survey of those who’ve posted stats on his swims). Sun Yang carried stroke length efficiency to the highest degree we’ve seen (for that distance). Try to hold just 200 meters a SL of 75% of your wingspan at any tempo you are able to and you will realize how amazing his stroke refinement and control really is.
This correlation between Sun Yang’s W/H Ratio and his exceptionally long and WR producing stroke, and that of many others, suggests that W/H Ratio can further help us dial in our SL Sweet Spot.
If my Stroke Length is not long enough how do I improve it?
For those who are reading this article and realize their stroke is too short, I bet 7 out of 10 swimmers have a drag problem holding them back, not a power problem. They need better body shape and control, not more muscles or more cardio-vascular strength (not yet, at least).
The basic solution is this: we have to reduce drag. And we have to cut it down ruthlessly. Drag grabs onto poor body shape and holds it back, like a mud pit sucks on the wheels of a car. Massive amounts of drag are removed by improving Balance, improving Passive Streamline positions, and then improving the transitions between them, or what we call Active Streamlining.
No increase in swimming hard or long will improve this – that will just make us more tired and no faster. Only a reprogramming of the neuro-muscular system will reduce drag and improve stroke length.
And, frankly, that is what all the Level 1 Total Immersion coaching, lessons, camps, and self-coaching materials focus on. Since 90% of the swimmers we see around the world are in this category of inefficiency, this is what a great portion of our teaching materials and training events address. It makes sense. It’s like triage for swimmers. It’s really fun when we get to work with swimmers beyond this point too.
But really, there is little point in working on Tempo and Beyond until we have control over Stroke Length, because Tempo means nothing unless it is linked to steady Stroke Length. Keep that image of wheels spinning in the mud in mind – making those arms spin faster means nothing unless those arms also make you cover more distance. This is why Stroke Length is the first thing we must address on the Path to swimming speed.
Don’t worry. We will address Tempo in the subsequent post. And my blog posts here are filled with stuff about The Beyond.
If my stroke length is OK already, what do I do with it now?
That depends on where you want to go!
The short, general answer is that you need to start challenging your Stroke Length to expand your adaptability to a wider range of conditions.
- Can you switch your ideal Stroke Length on command like switching gears on your bicycle?
- Can you hold your ideal Stroke Length in a range of Tempos?
- Can you hold your ideal Stroke Length over longer distances?
- Can you hold your ideal Stroke Length in the rush of the first length? Can you hold it in the exhaustion of the last length?
No? Here are a few first suggestions on how to work on those. The list could be endless once we start mix and matching these metrics.
- Learn to switch your SPL into any one of those 3 point in the SPL Sweet Spot on demand, and do it by feel. Train in them and switch them around so often that you can begin to feel exactly what a N SPL feels like, N+1 SPL feels like, and an N+2 SPL feels like within your first 3 strokes.
- Add tempo control – use a Tempo Trainer to challenge yourself on both the extreme slow side of your tempo comfort zone and the extreme fast side of that zone.
- Increase distance of the intervals you swim – set your SPL and hold it for that distance.
- Instead of trying to make the Stroke Length longer, find ways to make it easier. Doing any of the previous challenges will push you toward this objective.
View the whole Metrics Series:
- Metrics 101 – Stroke Length
- Metrics 101 – Aim For Stroke Length Ease
- Metrics 101 – SPL Development Process
- Metrics 102 – Tempo
- Metrics 102 – Slow Tempo
- Metrics 102 – Fast Tempo
- Metrics 103 – Pace
- Metrics 103 – Pace Construction
- Metrics 103 – Pacing Failure and Success
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